Applications Of Gold Nanoparticles In Polymer Solar Cells And Quantum Dot Light Emitting Diodes

Due to their simple fabrication procedure,physical flexibility and low cost,polymer solar cell(PSCs) have attracted great attentions.QD based quantum dot light emitting diodes(QLEDs) have potential to be the next generation solid state lighting source for display and illumination due to its size-tunable emission wavelength, narrow emission full width at half maximum(FWHM), high PL QY and thermal stability. However, the eifficiency and stability of polymer solar cells and quantum dot light emitting diode device are still need to be enhanced for the commercial applications.This paper mainly focused on the conversion efficiency of PTB7:PC71BM or P3HT: PCBM-based polymer solar cells and the performance of CdSe /CdS /ZnS-based quantum dot light emitting diodes. The incorporation of the Au NPs in different functional layers provided remarkable improvements in the performances of both OLEDs and OPVs, which benefitted from the surface plasmon resonan of the Au NPs.The work in this thesis can be summarized as follows:(1) Applications of Au NPs / ZnO nanostructures in PTB7: PC71BM-based inverted polymer solar cell:In this work, we investigate the near-field plasmonic resonance effect of Au nanoparticles(NPs) on the performance of inverted polymer solar cells by using solution-processed ZnO nanoparticles as the electron transport and buffer layer. The short-circuit current density, JSC, of PTB7:PC71BM based inverted polymer solar cells, is increased by more than 10% after incorporating Au NPs due to the plasmonic resonance enhancement effect, leading to an improved power conversion efficiency of ηP = 8.23%. The layer of ZnO NPs is proved to be very important to achieve such high device performance. The electron transport within devices can be greatly facilitated due to the high electron mobility of ZnO NPs, while the direct contact between Au NPs and active layer can be prevented by ZnO buffer layer, therefore effectively suppressing the interface exciton quenching and improving the device efficiency.(2) Applications of the dual Au NPs nanostructures inP3HT:PCBM-based inverted polymer solar cell:Light absorption improvement of P3HT: PCBM solar cells by embedding Au nanoparticles in MoO3 layer close to the metal electrode. Comparing to the control device, the incorporation of Au nanoparticles in MoO3 improves the current density of P3HT: PCBM solar cells dramatically with the increase of power conversion efficiency.We believe it is the back scattering effect of the Ag nanoparticles that improved the light absorption. In addition to evaporation 5nm Au NDs in MoO3, Au NPs is incorporated between ITO electrode and ZnO ETL layer.The PCE of double LSPR device with 5 nm Au NDs and 20 nm Au NDs increase from 2.9% to 3.65% compared with the standard device.The plasmonic resonance effect induced by Au NPs, which enhance the local electromagnetic field and improve light harvesting in solar cells.(3) Applications of Au NPs / PEDOT:PSS nanostructures in CdSe /CdS /ZnS-based quantum dot light emitting diodes:First the CdSe / CdS / ZnS-based quantum dots red light-emitting diodes are prepared and optimized, the standard device as follows: ITO / PEDOT: PSS / TFB / QDs / ZnO / Ag. The Au NPs is incorporation between ITO electrode and PEDOT:PSS HTL layer.Then the Au NPs / ZnO nanostructures is applyed in the QLED, and studied the impact of Au NPs on luminous efficacy of the device. We found that this effect is mainly due to the energy transfer between excitons of the light-emitting layer and the metal surface plasmon.